The power control strategy is very important to the operation of a motor vehicle.
Generally, the output power of an electric vehicle is controlled by the torque. When the accelerator pedal is depressed, the motor controller of the electric vehicle calculates the output torque of the motor according to the position of the accelerator pedal to control the vehicle. The output torque of the motor has a linear relationship with the position of the accelerator pedal, namely T0=T*Gain, wherein T0 is the output torque of the motor, T is the maximum output torque of the motor at the current speed which can be obtained by the corresponding curve relationship of the maximum output torque of the motor and the motor speed, and Gain is the position of the accelerator pedal. So the output torque of the motor is determined by the position of the accelerator pedal. During vehicle acceleration, if a larger output torque is needed the position of the accelerator pedal should be increased.
The power performance of the vehicle is determined by the accelerator pedal precision. When utilizing the detected position of the accelerator pedal, the motor controller needs to eliminate the noise in the position of the accelerator pedal using wave filtering to ensure that the calculated position of the accelerator pedal correctly reflects the operation of the operator. But the method of controlling the power output using the position of the accelerator pedal is difficult to respond the operation of the operator quickly and correctly.
However, for a four-wheel drive pure-electric vehicle, there is a higher demand for the power performance of the vehicle. Thus the power control strategy should determine the driver's demand in a short time and execute the demand quickly. The power of the four-wheel electric vehicle is always controlled by the main drive motor and the auxiliary drive motor. Currently, the main drive motor and the auxiliary drive motor are controlled using the power output method of traditional vehicles, that is, the output torque is controlled by the position of the accelerator pedal. In this method for the auxiliary drive motor, it is difficult to respond the driver's demand quickly and reach the power output with high precision. Also this accelerator control strategy is a waste of vehicle energy.